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Glider near miss with Airliner (emergency climb) near Chicago yesterday?

Take a peek at Flight Aware for almost any Class B at which you look. Right now, KORD, 4000 msl 280 kts for a SW 737. Night, junky weather, 1am local, so not much glider worries. But, it has been my observation there are not many air Traffic Cops worried about Part 121 speeders. Perhaps that is an entirely different thread.

Cindy B, excellent points made in your post.
Regarding the speeds, I have found ATC very diligent at monitoring speeds. I've been asked to verify my speed of 250 Kias or less, several times when I am right at the limit. ATC does not even have authority to approve more than 250 Kias. They can approve an increase above the 200 kias limit under class B or in the vfr corridor of class B, but the 250 kias limit is a hard limit. Looking at the flightaware speeds is a little misleading because those are true speeds, does not factor in winds, and are computed based on position change. There is no way to know exactly what the indicated air speed is for the aircraft at a specific point, unless you are in the aircraft.

Glider near miss with Airliner (emergency climb) near Chicago yesterday?

Take a peek at Flight Aware for almost any Class B at which you look. Right now, KORD, 4000 msl 280 kts for a SW 737. Night, junky weather, 1am local, so not much glider worries. But, it has been my observation there are not many air Traffic Cops worried about Part 121 speeders. Perhaps that is an entirely different thread.

Cindy B, excellent points made in your post.
Regarding the speeds, I have found ATC very diligent at monitoring speeds. I've been asked to verify my speed of 250 Kias or less, several times when I am right at the limit. ATC does not even have authority to approve more than 250 Kias. They can approve an increase above the 200 kias limit under class B or in the vfr corridor of class B, but the 250 kias limit is a hard limit. Looking at the flightaware speeds is a little misleading because those are ground speeds that are effected by wind speed and direction. The speeds are also computed based on position change, so it is an approximation of ground speed. There is no way to know exactly what the indicated air speed is for the aircraft at a specific point, unless you are in the aircraft. Flightaware is great to see the patterns of flights in a general area, see the typical altitudes, and to realize how fast some of the aircraft are traveling at low altitude.

Again, because many of us throw the 250 number around so frequently, most pilots forget that the number is "indicated airspeed"; and that 250 kias at 10,000 ft, is really 300 knots.

For those that wonder why the controllers want everyone low at the same alititude, remember the systems they are using. It is a good idea to go visit a center and/or tower. The systems are all a flat screens that are great at projecting potential flight paths at the current speeds. The systems and the humans are great at visualizing these horizontal components. It is more difficult to visualize and manage the vertical component of altitude. Likewise, aircraft can maintain an airspeed very well which makes horizontal speeds more consistent. Vertical speeds are more difficult to predict and control by the computers and controllers. Every center and tower I have visited have been staffed by some of the nicest and most professional staff you will ever meet. I have witnessed a few stressed and angry controllers on the radio, but the vast majority are a great resource and well trained. It would be a shame to see it privatized and screwed up.

Glider near miss with Airliner (emergency climb) near Chicago yesterday?

Vertical speeds are more difficult to predict and control by the computers and controllers.

Bingo! I think we finally solved the mystery as to why the hell ATC seems to be so inclined to drag airliners in low. The problem boils down to the fact that during descent, an airplane is inherently occupying a much greater volume of airspace then they are in level flight. Far out, there is plenty of room to accommodate that uncertainty volume that the airplane needs while descending. As you get closer to the terminal, there is less volume to work with (1/r^2) and the controllers are wanting tighter control which they can get with level flight and smallish altitude changes.

I don't like it one bit, but that's undoubtedly why it's happening. ATC needs to recalibrate the risk that they're taking by running heavies through airspace shared with gliders. As others have pointed out, they're likely oblivious to how prevalent gliders are and how hard we are to see and avoid.

Glider near miss with Airliner (emergency climb) near Chicago yesterday?

----ATC needs to recalibrate the risk that they're taking by running heavies through airspace shared with gliders. As others have pointed out, they're likely oblivious to how prevalent gliders are and how hard we are to see and avoid----

I'd say this goes both ways. We as GA glider pilots need to recalibrate the risk we take when operating near Class B and busy Class C airspace. That airspace does not "belong" to us as VFR aviators, it's mutual use see and avoid airspace. You should know the hot spots and avoid them, you should have a transponder (turning it on would be nice), and maybe even talk to or monitor ATC occasionally. Or we can complain to the Feds about heavy metal flying thru "our airspace" until the Feds decide "your right, that is high risk, I'll think we'll double the size of the Class B/C airspace. Thanks for the input glider dude". We are very fortunate to have the airspace access we have here in the good ol USofA. I don't wanna look like Europe.
WR

Glider near miss with Airliner (emergency climb) near Chicago yesterday?

On Saturday, October 7, 2017 at 11:34:17 AM UTC-4, Steve Koerner wrote:
Vertical speeds are more difficult to predict and control by the computers and controllers.

Bingo! I think we finally solved the mystery as to why the hell ATC seems to be so inclined to drag airliners in low. The problem boils down to the fact that during descent, an airplane is inherently occupying a much greater volume of airspace then they are in level flight. Far out, there is plenty of room to accommodate that uncertainty volume that the airplane needs while descending. As you get closer to the terminal, there is less volume to work with (1/r^2) and the controllers are wanting tighter control which they can get with level flight and smallish altitude changes.

I don't like it one bit, but that's undoubtedly why it's happening. ATC needs to recalibrate the risk that they're taking by running heavies through airspace shared with gliders. As others have pointed out, they're likely oblivious to how prevalent gliders are and how hard we are to see and avoid.

If that airliner goes over us in level flight at 9000 instead of 6000, it isn't consuming any more volume. It does possibly eliminate one descent step for the approach controller which is likely why they do it.
UH

Glider near miss with Airliner (emergency climb) near Chicago yesterday?

On Saturday, October 7, 2017 at 4:36:45 PM UTC-7, wrote:
If that airliner goes over us in level flight at 9000 instead of 6000, it isn't consuming any more
volume. It does possibly eliminate one descent step for the approach controller which is likely
why they do it.
UH

What Steve was trying to say is that if the plane were to be flying a steady descent from 9 to 6 it would be consuming ALL the airspace from 9 to 6, not just the diagonal vector. So they cannot vector a plane at 7k across that path because it's *possible* that the plane will descend from 9 to 6 in less than a mile vs. the hoped for gentle descent.

Glider near miss with Airliner (emergency climb) near Chicago yesterday?

What Steve was trying to say is that if the plane were to be flying a steady descent from 9 to 6 it would be consuming ALL the airspace from 9 to 6, not just the diagonal vector. So they cannot vector a plane at 7k across that path because it's *possible* that the plane will descend from 9 to 6 in less than a mile vs. the hoped for gentle descent.

5Z

Yes, exactly Tom. The further out that they can get an airliner low, the less airspace they will consume getting him down in close to the vicinity of the terminal where the airspace is more precious.

Glider near miss with Airliner (emergency climb) near Chicago yesterday?

"250 kias limit is a hard limit"
I need to clarify my previous post. I should have stated, "250 kias limit is a hard limit for civilian aircraft". One of the things Wes made me aware of when getting an orientation at Seminole, is that there is a military IR route just west of the airport over the green swamp. As most pilots are aware, the military can exceed the 250 kias limit on their training routes even below 10,000. Even below 1,500 ft in some cases. The military speed limit below 10,000 ft is 420 kias and their "minimum" speed is usually 300 knots. Many of the routes are for IFR military training and they are under the control of ATC and possibly not looking out the windows. Flying near these routes without a transponder would not seem prudent. ATC is keeping other IFR traffic out of the area. If a VFR pilot ventures into one of these routes, then the VFR pilot should probably assume they have full responsibility for separation.

I have not seen it discussed previously, or I may have missed it. I have had reservations about flying near airways or crossing airways in the glider.. As most gliders are certified in the experimental category, the FAR rule about not flying over densely populated areas and "in a congested airway" applies. Since I have Mode S transponders in my gliders, I am aware that ATC can see exactly where I am and who I am. I have never seen a definition of "congested". I have monitored the traffic on airways near where I primarily fly, both via ADSB-IN in my other aircraft and using Flightaware. I think I could justify that the airways I cross are not "congested", but the term is obviously subject to some interpretation. In the case of the United246 incident, there are many airways in the area. Most of the airways have a minimum altitude for IFR traffic less than 3000 ft. Likewise, since STARS into ORD use some of the airways, then those might be considered congested, or at least frequently used airways. If it is not permissible to fly in a congested airway, then it seems an argument could be made that we must fly under it?

Glider near miss with Airliner (emergency climb) near Chicago yesterday?

"the 250 kias limit is a hard limit"

I need to clarify my previous post. I should have stated, "250 kias limit is a hard limit for civilian aircraft". One of the things Wes made me aware of when getting an orientation at Seminole, is that there is a military IR route just west of the airport over the green swamp. As most pilots are aware, the military can exceed the 250 kias limit on their training routes even below 10,000. Even below 1,500 ft in some cases. The military speed limit below 10,000 ft is Mach 1 although they typically fly somewhere between 300 kias and 420 kias. Many of the routes are for IFR military training and they are under the control of ATC and possibly not looking out the windows. Flying near these routes without a transponder would not seem prudent.. ATC is keeping other IFR traffic out of the area. If a VFR pilot ventures into one of these routes, then the VFR pilot should probably assume they have full responsibility for separation.

I have not seen it discussed previously, or I may have missed it. I have had reservations about flying near airways or crossing airways in the glider.. As most gliders are certified in the experimental category, the FAR rule about not flying over densely populated areas and "in a congested airway" applies. Since I have Mode S transponders in my gliders, I am aware that ATC can see exactly where I am and who I am. I have never seen a definition of "congested". I have monitored the traffic on airways near where I primarily fly, both via ADSB-IN in my other aircraft and using Flightaware. I think I could justify that the airways I cross are not "congested", but the term is obviously subject to some interpretation. In the case of the United246 incident, there are many airways in the area. Most of the airways have a minimum altitude for IFR traffic less than 3000 ft. Likewise, since STARS into ORD use some of the airways, then those might be considered congested, or at least frequently used airways. If it is not permissible to fly in a congested airway, then it seems an argument could be made that we must fly under it?

Glider near miss with Airliner (emergency climb) near Chicago yesterday?

Heavy transport category aircraft are authorized to exceed the 250KIAS limit in the climb below 10,000 MSL when required to maintain a safe speed margin in clean configuration.

Military fighters do the same and often climb out at 350KIAS below 10,000 MSL. Many jet fighters descend at 300 KIAS below 10,000 for the same reason having the ability to maneuver while clean.

IR routes for military use are often used in VFR weather. VR routes require higher weather mins to used.
Speeds in a IR/VR route and MOA can routinely exceed 500KIAS to .99 Mach. at altitudes down to 500ft AGL.